Work machines, such as those in the forestry industry, are often required to balance the amount of power distributed to various performance characteristics and operations. For instance, a machine may include a boom and work implement to complete a desired task. The amount of power produced by the engine is shared throughout the machine to move the machine along different terrain and also operate the boom and work implement. In some instances, it is desirable for the machine to travel at a high speed, whereas in other instances the machine may be stationary and work is being done by the boom and work implement. In any event, it is desirable to optimize machine performance.
Some machines utilize one or more hydraulic motors to provide torque to drive the machine forward and backward. The machine can include an engine that produces power and drives a hydraulic pump. The pump can provide hydraulic fluid to the one or more hydraulic motors through a control valve. Each hydraulic motor can be a variable displacement motor, such that at a minimum displacement the machine can move at a high speed and at a maximum displacement the machine travels at a lower speed. At a maximum displacement, however, a greater amount of torque can be provided to drive the machine over difficult terrain, an inclined slope, etc. The manner in which motor displacement is controlled on a variable displacement hydraulic motor is through a predefined “start of control” pressure (SOC) that is mechanically fixed and it is difficult to make any adjustments to the displacement setting. The “start of control” pressure is a defined pressure at which the motor displacement begins to increase due to an increased load on the motor. The lack of adjustability prevents the machine from performing at optimal levels of performance in nearly every possible scenario.
A need therefore exists to provide a means for adjustably controlling the “start of control” pressure of the motor to better optimize machine performance. Moreover, it is desired to be able to make these adjustments continuously and as a function of how a machine operator is controlling the machine in real-time.